How the Grid Works

Why every hour matters for clean energy — an interactive data story using EIA hourly generation data across America's grid regions

Choose Your Grid Region

Click a region to explore its unique energy story. Each region has a different generation mix and clean energy challenge.

Every Hour of Electricity Generation in 2024
Each dot is one hour. Color shows grid emission intensity: blue = clean, red = dirty
The Clean Baseload: Nuclear + Hydro, Every Hour
Blue area = clean firm generation (nuclear + hydro). Gray area = total grid load. The blue band barely wavers.
A Typical Summer Day: How the Stack Dispatches
Stacked generation by source across 24 hours. Fossil fuels ramp up as demand rises.
Wind + Solar by Month: When Nature Delivers
Top two rows: wind. Bottom two rows: solar. Each tile is one month's average 24-hour profile.
Annual Average vs. Hourly Reality
Left: the single annual number. Right: every hour revealed. The average hides the chaos.
Two Hours, Same Grid, Different Worlds
A clean hour vs. a dirty hour. The resource mix changes dramatically.
Where the Energy Comes From
Energy flow from generation sources to the grid. Clean vs. fossil, in TWh.
Act I

The Grid Never Sleeps

Right now — this very second — grid operators are orchestrating a symphony of thousands of generators to deliver electricity to millions of homes, hospitals, data centers, and factories.

Every hour, they must perfectly balance supply with demand. The margin for error is razor-thin: even a small imbalance can cascade into blackouts.

TWh in 2024
Hours/year
GW avg load

What you see is every single hour of electricity generation in 2024 — 8,760 dots. Each one represents the grid's output during that hour.

Blue and green dots are the cleanest hours: nuclear, hydro, wind, and solar carried the load. Orange and red dots are the dirtiest: fossil generators were ramped to maximum.

The size of each dot reflects total generation — bigger dots mean more power flowing through the grid during that hour. Notice how they swell during summer peaks and shrink in the quiet overnight hours.

This is the electricity system that powers modern life. It's vast, variable, and always changing. And yet conventional carbon accounting treats every hour as though it were the same.

Scroll to discover why that assumption is dangerously misleading.

Act II

The Baseload Foundation

Nuclear and hydroelectric power form the grid's clean, firm foundation. They run 24/7/365 regardless of weather.

Look at the blue band — it barely moves. That's the steady, unwavering stream of carbon-free power that anchors the grid every single hour.

GW avg clean firm
24/7
Always on
Act III

When Demand Rises, Fossil Fuels Answer

As demand climbs each morning, fossil generators ramp up. First efficient gas, then dirtier units: peakers, oil, coal.

Clean (0 kg CO₂/MWh)Dirty (high emissions)

The emission rate of every MWh changes dramatically by hour.

Cleanest hours
Dirtiest hours
Act IV

The Renewable Revolution — It's Not That Simple

Wind and solar have transformed the grid. But they generate when nature allows, not when needed.

Summer midday: solar floods the grid. Winter evenings: almost nothing. The pattern is dramatic and seasonal.

The transition isn't just more renewables. It's reliable + affordable + clean.

Act V

The Annual Accounting Illusion

Annual Scope 2 gives one number. It looks clean. Reassuring.

But behind that average hides chaos. Some hours are nearly zero-carbon. Others are heavily fossil-fueled.

A company "matched" at 100% annually may still cause emissions during thousands of hours.

Avg fossil share
High-fossil hours
Act VI

Every Hour Tells a Different Story

Same grid. Two hours. Radically different resource mixes.

The clean hour is dominated by nuclear and renewables. The dirty hour has fossil fuels stacked high.

Hourly accounting reveals what annual numbers hide.

Act VII

The Path Forward

The transition: from reliable + affordable to reliable + affordable + clean.

Hourly matching tells markets: "We need clean power at 6 PM in January, not just sunny April afternoons."

This drives investment in firm clean power, storage, and demand flexibility.

See What Hourly Matching Means for Your Portfolio

Our Hourly Clean Energy Calculator estimates your hourly Scope 2 emissions using proposed GHG Protocol revisions.

Explore the Hourly Calculator →